Thanks to Jack for the invitation to offer a guest post on Brexit developments from the other side of the Atlantic. This is a follow-up to Sandy Levinson’s excellent analysis, which heaps (well-deserved) scorn on politicians in the UK. My aim here is to provide an update, to describe the British institutional framework (such as it is) and to identify the upcoming challenges to the political system of the United Kingdom.

The recent vote in the UK to withdraw from the European Union has put its constitution under exceeding stress. The constitution of the United Kingdom is famously uncodified. It is not unwritten, as it consists of written statutes, as well as unwritten precedents and principles. But it’s a fluid, political constitution, which is generally understood to be adaptable to changing circumstances. Constitutional statutes generally include monumental acts (for lack of a better term), such as the ones dealing with the 1706/07 Union between Scotland and England (and Wales) but also the European Communities Act 1972, by which the UK joined the EU in the first place. One important precedent, as Sandy points out, is that the monarch does not withhold royal assent from acts of parliament; although the royal assent is required, the unelected monarch is not a political actor and so approves whatever legislation parliament hands to her. Constitutional principles are general notions like the rule of law and parliamentary sovereignty.

Parliamentary sovereignty has long been a vulnerable notion: technically, it means that only parliament can make a law, and parliament can (by a simple majority) legislate on any matter whatsoever, except that it cannot bind future parliaments. (The rule-of-law principle was theoretically what kept parliament from legislating to violate fundamental rights and privileges, e.g. by abolishing private property.)

The EU’s jurisdiction over UK domestic law was one nail in the coffin of parliamentary sovereignty; others have included the generally exclusive jurisdiction of devolved parliaments in Scotland, Wales and Northern Ireland, and (to a more limited degree) the UK courts’ ability to adjudicate matters of human rights. Use of referenda is yet another. All of these have transformed parliamentary sovereignty in its pure form from a constitutional principle into a legal fiction. Indeed, as my colleague Iain McLean has shown in What’s Wrong with the British Constitution, even in its heyday parliamentary sovereignty allowed for both mendacity and hypocrisy, as when parliament decided in 1912 that the Irish should have Home Rule, but the leader of the opposition, Andrew Bonar Law, suborned gun-running and mutiny among Unionist Protestants there.

The vote to Leave on June 23 is putting the entire parliamentary system to the test. Constitutional principles like parliamentary sovereignty are legal, not political, principles. Even the great champion of parliamentary sovereignty, A.V. Dicey, admitted that political reality could bind parliament in a way that law could not: ‘[I]t is hardly conceivable that a modern Parliament [given the consequences of the Boston Tea Party] should wish to tax the Colonies.’ Indeed. Here is where the ‘advisory’ character of the vote to Leave weakens along with parliamentary sovereignty. Turnout in the election was 72%, the highest in a UK-wide election since 1992. A model by the political scientist Chris Hanretty estimates that 421 out of 574 English and Welsh parliamentary constituencies voted to Leave. Thus, most MPs’ constituencies favoured the outcome. David Cameron repeatedly promised that a Leave vote would bind his government, and Theresa May seems to intend to stick with that promise. She has tautologically announced, ‘Brexit means Brexit’. Critics of the result (myself among them) may wish to minimize the adverse impacts of the vote, but something less like EU membership is politically necessary for the UK, even though, before the referendum, a majority of MPs opposed Leaving. Legally, the referendum may be advisory; politically it is not. Sandy is, once again, right to point out that the institutional mechanics of referenda in the UK have never been thought through, but this time they will work this way: a typical instance of empirical English constitutional ad-hockery.

But Theresa May’s tautology (‘Brexit means Brexit’) does not help. What does Brexit/Leave mean in practice? The first step is triggering Article 50 of the Treaty on European Union, which starts a clock that must result, within two years, in an agreement on the terms on which the UK Leaves. If no agreement is reached, then the UK reverts to WTO rules and will have to absorb a swinging 5–10% tariff on goods exported to the EU (not to mention the limitation of trade with the banking sector, which in 2013/14 contributed £21.4 billion to UK tax receipts). More importantly from a legal standpoint, an abrupt departure will end workers’ and others’ rights, which have been confirmed by domestic statute enacted pursuant to UK law (think working hours and parental leave).

This has created a legal controversy, initially sparked in an article by my colleagues Nick Barber and Jeff King, along with Tom Hickman, who argue that parliament must approve the invocation of Article 50. Their reasoning is that if the government invokes the article without parliament’s consent, it will do so by using the Royal Prerogative (the inherent power of ministers of the crown), but that the Royal Prerogative cannot be used in derogation of a statute. Others disagree. (Theresa May has not committed herself, but in the past she has been critical of use of the Royal Prerogative.) Delaying Article 50 preserves the UK’s first mover advantage, while events continue to develop, and allows for the consequences of Leave (particularly the adverse economic ones) to sink in with the UK’s voters, but it also risks making EU leaders impatient as their economies suffer from uncertainty. They have said they will not negotiate, even informally, until Article 50 has been triggered.

Because the UK has a very limited number of institutional veto players (individuals or groups whose agreement is necessary to change the status quo: remember, the Queen doesn’t withhold the royal assent), the political system depends heavily upon partisan veto players, which arise based on particular issues and which must be cohesive to be effective. These have all gone AWOL, as Sandy also points out.

One might wonder why the Conservatives would change leaders at this point. The answer is fairly clear. While Leavers wrote to David Cameron before the result was known, asking him to stay on no matter the result, the premiership became a poisoned chalice for him on June 24th.Had he stayed, he would have been criticised if he had given even an inch to the EU negotiators, including on the most salient topic, immigration, and he had already done his best in the run-up to the referendum, which he attempted to use as leverage to renegotiate the terms of the UK’s membership. He would also have been criticized for the economic downturn which is bound to follow the referendum (even though he had warned about it during the campaign).Because of the lack of veto-players, the government is responsible for everything!

Leaver candidates for the premiership self-destructed: Boris Johnson spent Saturday, June 25 playing cricket with Charles Spencer (the ninth earl Spencer and brother to the late Princess Diana) at Spencer’s estate Althorp (pronounced áwl-trup); after using that weekend to his advantage to gather Conservative MPs’ support, Michael Gove was rejected by Conservatives because he had been disloyal to Boris; and the most recent finalist, Andrea Leadsom, was disqualified and had to withdraw from the contest, because she gave an interview in which she said that she would be a better Prime Minster because she was a mother and had a real stake in the future (her opponent had recently admitted to the sadness she experienced from not being able to have children).

Theresa May has followed Cameron as Conservative leader, essentially by acclamation and necessity. And, Labour is currently engaged in a 1970s-era, internecine struggle between its hard left leader, Jeremy Corbyn, backed by the iron shadow chancellor John McDonnell, and the softer centre of the party who see Corbyn’s leadership (particularly in his half-hearted opposition to Leave) as hopeless. For more on this debate and how it is playing out amongst graduate students in politics see the posts here, here, here and here. Most importantly, however, Theresa May has a working majority of twelve. Once we begin to find out what Brexit really means, that number is sure to dwindle. With a thin Conservative majority and no currently effective opposition, veto players are uncertain and undependable.

A general election? Well, that’s complicated. In the old days, a no-confidence vote in the House of Commons would have brought down the government. That would not have led to a general election unless no alternative government could be formed, and prime ministers have succeeded to office more than half the time without a general election in the last 100 years. However, the system has recently changed. General elections now take place every five years in the UK, and the next one is scheduled for May 7, 2020.

In the old days, when a prime minister either lost the confidence of the House of Commons or wanted to increase her majority, she could go to the palace and ask the monarch, in an exercise of her personal royal prerogative, to dissolve parliament and call a general election. At present, however, the options are limited by the Fixed-Term Parliaments Act 2011. Now, in order to call an early election, parliament must either (1) vote by two-thirds of its total membership to hold an election; (2) vote (by a simple majority) that the government lacks confidence and fail to affirm its confidence in another government in two weeks; (3a) repeal the act (by a simple majority); or (3b) vote to have an early election (by a simple majority) and state that the act does not apply to the election.

The first option is probably unachievable, and the second would require a vote by Conservatives that they lack confidence in a newly elected leader: unlikely for now. Repeal of the act is also unlikely, because it took a royal prerogative from the Queen, and no royal prerogative has been reinstated once abolished. The fourth work-around is the most likely. While the Liberal Democrats have called for a new election, they currently have eight seats. Labour is in such disarray that not all of its members can be counted on to do anything together. So a new election will depend on a combination of parties, but it will also require the support of the government, because option 3b requires the government to give parliamentary time for such a bill. A general election will only take place when the government is unable to govern and admits as much: that will not be a pretty situation.

These are just the procedural constitutional quandaries that the UK faces in light of the referendum vote. What substantial meaning Leave may have (Norway-style membership in the European Economic Area; Swiss-style membership in the European Free-Trade Association; or some variant thereof) is completely unknown. The basic point, however, is that the institutional, governmental and constitutional procedures that will decide that outcome are all highly doubtful. In the past, the combination of a strong government majority and a weakened opposition has not presented existential danger (see 1983 and 1997 for details). But in these uncertain times, and with a small working majority, there are too many moving parts.

Once upon a time, as in 1931 following the stock market crash, the monarch could call in the heads of parties, bang heads together and ‘request’ that they form a national government. In these times monarchical intervention like that is highly unlikely. What will be needed, however, and is also highly doubtful, is that the parties will be able to abandon their tribalism and cooperate to prevent the next ten years from becoming an economic and political disaster. The UK’s constitution may adapt, over the long term, to changing circumstances, but its institutional foundations (such as they are) provide little reassurance for those of us who want to believe that the country will navigate itself out of the present mess.

Scot Peterson is the Bingham Research Fellow in Constitutional Studies at Oxford University. He teaches British politics. You can reach him by e-mail at scot.peterson at balliol.ox.ac.uk